Coordinate selecting and lockout circuit



Feb. 20, 1951 G. HECHT 2,542,672

COORDINATE SELECTING AND LOCKOUT CIRCUIT Filed Oct. 27, 1948 2 Sheets-Sheet l //v VENTOR 6. HE CH T AT TORNEV Feb. 20, 1951 HECHT 2,542,672

COORDINATE SELECTING AND LOCKOUT CIRCUIT 2 Sheets-Sheet 2 Filed Oct. 27, 1948 N ill MM-lv PQ I I I T /Nl/ENT0R G. HE CH7 7,

ATTOBNEV Patented Feb. 20, 1951 COORDINATE SELECTING LooKoUT GIRCUPP George Hecht, Astoria, N. Y., assignor to Bell Telephone Laboratories," Incorporated, New

Yorli, N. Y., a corporation of New York Application ctob'er27, 1948, Serial No. 56-,89-1

, 1 Claim. 1-

This invention relates generally to improve ments of lock-out control circuits and more specifically it relates to improvements of lock out control circuits for coordinate switching ar rang'em'ents employing cold cathode, gas-filled tubes;

An object of the invention 'is to provide arrangements for interconnecting one of a first groupof circuits'to one of a second group of cir cuits' with a reliability-"and accuracy heretofore unknown in the art.- I

A further object of the invention is an ar- I ran ement wherebyno'two or more circuits of vlock-out circuit disclosed in a copen'ding'applica tion for atent by E; Bruce, serial No. 42,354, filed August 4, 1 948, which discloses a lock-out control circuit utilizing four electrode cold cathode gas tubes arranged in coordinate fashion. In said Bruce application the control cathodes in a horiaontal'row; thecontrol anodes in a vertical column, and the main anodes in a non zontal row, are all connected in multiple; lockout may first occur in a vertical column and then subsequently occur in a horizontal row, the tube becoming ionized in the main discharge path being common to both the horizontal row and 'the'v'ertical coluinn'; each of the aforesaid c'onnectionsin multiple has an I impedance com mon to all theelectrodes" in a particular multiple connection.

-' For purposes of clarity the coordinates will be designated as horizontal rowsend vertical col divi iiual impedance-are in the circuit in which the firstgroup of circuits becoming connected to one" of the second group of circuits; or two or more ofthe-second group of circuits becining connected to one of the first group, i-f the gas tubes of a row or column-haveno individual impedancesi-n their respective lock-out circuits. The prior Bruce application referred to, supra, disclose such-impedances individual to each gas tube in a column. V U

The present invention embodies improvements whereby the probability of operational failure from such reasons as discu ssed supra are considerably less" thanhas been known heretofore. Here there are no impedances individual to each gas tube 'of a column or row in the circuits in which lockout occurs. I a

Inaccordance with an exemplary embodiment of this invention 'offive-element gas discharge tubeis-emp o yed, having-a screen; or g-r-id shield-- in the main anode and arranged so that a discharge must be first initiated" to the screen before itcanbe transferred to the main anode. This tubeisemployed-ina multiple or coordinate lock-out circuitsuch that only one path "will be completed from one circuit-of a first group of circuits to acircuit of a second groupercircuits. The tubes and'circuits are arranged such that 'certain'elements ofthe tubes are arranged in a generic aspect ofthe inventiongroups'of cirrip. "1 niecold cathode gas" tubes scares tubes 9, 24, 29, etc., have five electrodes. Electrodes 2 and 8 are the control anode and control cathode respectively and are utilized, among other purposes, for establishing an initial ionization within the tube. More commonly they are designated starting electrodes. The screen grid II envelope the main anode I9 to insure lockout before the main anode I9 acts as an electrode for a discharge. Electrode I6 is the main cathode of the gas tube. The tube in the preferred embodiment of the invention, may be argon filled since argon has superior lock-out characteristics, but other suitable gases, including neon, krypton, hydrogen, metallic vapors, etc., may be used. Construction of the tube must be such that when used in conjunction with suitable applied potentials the control anode control cathode gap ionizes first and the first transfer is from the control anode to the screen grid. A tube of this general type is disclosed in Depp, United States Patent r etc about .1 microfarad; resistance of relay 25,

etc, about 1500 ohms; resistances 32, etc., about 1,000,000 ohms; resistances 20, etc., about 600 ohms; resistances l8, etc., about 600 ohms; in-'- *dluctances I4, etc., about 20 henries, resistance 1 about 22,000 ohms, battery I! about 50 volts; and battery [2 about 130 volts. I i

The operation of the invention will now be described in detail. In the interests of clarity the operation of Figs. 1 and 2- will be taken up separately. i In Fig. 1 switch I is closed by an external means such as a sender. Thereupon battery 3 places positive 100 volts upon control anode 2 through inductance 4 and resistance 35. Ground is already on control cathode 8 by virtue of a circuit extending from ground through resistance '1, contact 6, a chain of contacts 5, to control cathode 8. The control gap of this type of gas tube will ionize at this voltage. Since all the tubes in a vertical column have this voltage applied across their control gaps, there would 'normally be a probability of more than one of the tubes in the vertical columns ionizing. However, inductance 4 and resistance 35 act in a manner well known in the prior art to reduce this probability to a very small value, Thus only one'of the gas tubes in the vertical row will have-its control gap ionized. Assume that tube 9 is that one. Condenser it has acted to keep the potential of control cathode 8 at ground during the ionizing period. Towards the end of the impulse, a matter of a few milliseconds, condenser Ill will no longer serve this purpose and the potential of control cathode 8 will become positive due to the current fiow therethrough and a resultant voltage drop across resistance I. The first transfer within the tube takes place between control cathode 8 and screen grid II which immediately before this ionization occurs has a potential of positive 130 volts from battery I2, contact I3, in-

utilized in this exemplary embodiment of the in vention the screen grid II surrounds the main anode and until an arc is first established with the screen grid as an electrode, an arc will not be established with the main anode as an electrode because the screen grid and the main anode are at the same potential when neither is acting as an electrode. Therefore there is a discharge, at this point in time, from screen grid I l to main cathode I6, hence the main anode Ill becomes capable of acting as an electrode for an arc. The transient current flowing through the screen grid circuit and inductance I4 produces a potential drop across inductance I4 which places screen grid II at a lower potential than main anode I9 thus permitting a transfer of the discharge to the space between main anode I9 and main cathode I6. It will be noted that the screen grids, the control cathodes, and the main cathodes in any one horizontal row are connected in multiple which is the best condition for lockout. This results in a double lockout in the horizontal'rows; the first being in the screen grid II and control cathode 8 circuit with inductance I4 and re sistance i constituting the impedance common to all such circuits in this horizontal row, the second being in the screen grid II and main cathode I6 circuit with inductance I4 and re- 'sistance 20 constituting-the common impedance to all such circuits in the horizontal row.

The first of the two lock-out circuits discussed supra, e. g. the lock-out circuit involving the screen grid II and the control cathode '8,'extends from positive battery I2, contact I3, common impedance I4, conductor I5, screen grid II, the space gap to control cathode 8, conductor 2 I, the chain of contacts 5, switch 6, common resistance 1, to ground. The second of the two lock-out circuits, e. g. the lock-out circuit involving the screen grid II and the main cathode, extends from positive battery I2, switch I3, common'inductance I4, conductor I5, screen grid II, the space gap to main cathode I6, conductor 22, common resistance 28, to negative battery 11. An important feature of these two lock-out paths lies in the fact that neither has impedances which are individual to each gas tube in any one hOIiq zontal row. i

It is to be understood that the above descrip tion is applicable to each row of tubes should that row be chosen by the vertical lock-out -cir+ cult. Up to this point little mention has been made of the usefulness and operation of the two lock-1 out circuits existing in any horizontal row. This will now be discussed. j Assume that two senders simultaneously 'require to be connected to a marker. Although two or more senders can be simultaneously con: nected to different markers only one sender can be connected to the same marker at the same time, so it becomes essential that no two or more tubes, corresponding to two or more senders-in one horizontal row become completely ionized at one time.

A difierent horizontal row must be selected for. each sender since there is only one marker avail=- able for each row. If two senders close switches I and 23-simu1taneously, there will'be a DOSSi'r bility that the vertical lock-out circuits heretofore described will operate to choose a tube in the same horizontalrow for both senders: As-v sum v that this occurs and that the control anode to control cathode space gap is ionized in both tube 9 and tube 24, Asexplained prior, the dis-e.

anteater-r] charges withinzth'e' .tubes will next attempt ;to

and: the screen. grids of: thertubes, in.;;th is., hori:, zontal row. are. connected in multiple and induct; anceal t and resistance; constitute. the; common impedancegwhich; prevents-the aforementioned transfer in alltbut oneof the tubes in this: hon-.- zontalrowxin a'manner Wellknown in theprior art; Shouldthe wrarepossibility occur. that a transfer to the screen in two aonmore tubesxis efiectedthere will still be. another. opportunity for lockout .to ..occur..' Asexplained. prior; the area within the .two tubes .will nextattemptr to :trans.-.

fer to the space gap between-.themain: cathode l Sand the screen-grid ll aselectrodes; Since both the screengrids and themain cathodes in;

aihorizontal' row; are: connected in. multiple. and there is a common'impedance, inductance It and resistance 29,- lockout of all but .one ofthe gas...

tubes :will almost certainly occur. The final transfer of the arc in theselected tube nowtalres place between the main cathode l5 and the main anode :19 to operate relay 25in a circuit extending from positive battery l2,- switch i 3, resistance l8, conductor 26, relay 2% main anode: 59, through the. space gap to main cathode iii, conductor 22, resistance .28, vto negative battery ll. Operation of relay 25 -opens contact 5 of said relay. Opening. of contact 5 will extinguish any discharge existingbetween the control cathode .-and control anode of any tube or tubes in thishorizontalmow-of tubes inasmuch as contact 5 forms apart of such circuit.

.It is important that. these discharges be extinguished. inasmuch as nosender, becoming con? nected to .a vertical row in which there is aclischarge at-the timeof. suchconnection between the control anode and control cathode of .atube 24 for example can become connectedto a marker during such discharge since none of the tubes in said vertical row can become completely ionized due to the ..fac.t that the discharge between the control anode and control cathode of tube 24has lowered thedifference of potential .of the corresponding space gaps of all other tubes in the same vertical column to aanpoi-nt below the breakdown va ue of said space gap. The lowering of said difference of potentialwould be caused bythe flow of the discharge current through resistance 28.and resistance 1.

But since contact 5 is opened, all the vertical columns, other than those in .use; are available to senders connected thereto. It is to benoted however, that no tube, in the same horizontal row as a fully ionized tube, can have a discharge created between its starting cathode and starting anode because the circuit therefore is opened when contact 5 is opened.

Consequently if a second sender shou d now close switch 23, tube 24 could not be ionized. But either tube 29 or tube 33 could be ionized. As described before either, but not both, tube 29 or tube 33 will ionize due to the lo k-out effect of resistance 28 and inductance 21. When a tube has com leted its function and has been extinguished by the opening of a switch such as [3, relay 25 will be deenergized and contact will close thus placing the corresponding horizontal and vertical coordinates again in normal condition.

Attention is now directed to Fig. 2 wherein the invention is applied to telephone circuits to 20 and associated-switches. It may be assumed 6"? connectsenclersto arkersz; .-.,'I'he .wltches-' and.:30 ofFigitiinowarethe armatureso l 9 land associated; contacts.- of Fig. 2; SW I 3 and ;6 iof; Fig. 1 .are inow; rarmaturcs oj.,; rela that .each. :relay. I 9 'is associated. with a send S I, 52, 53., etc.;. and .that..each.relay.; i 9: trolled byv its associated sender so that therel is energized to close its...conta cts whenever, the t sender requiresto ;be connected; tQa marke A1;

seriesof markers.are.;designated.MI, M2, M3, etc-e. and each-.- marker "has: associat d: herewith; relay: 20 which; is released whentheymarker is. idleand. availablezzand is OpfilfitQdgES. so 1 the =marker.- is :seized; remaining operate the -.marl er has :performedlts function telephonei'system. whereupon it, again. haw- 468. released. Incident tov the; release .of .r ay. closesrztwoiback; contacts: which; correspond spectively tothe switches 6:;and;l 3 of;;Fig,.; is understood. that switches 6 and J 3 {or ar tures .6 and J3) close "when relay zjflsisdeene gized; The tubes shown inFig. 1 are not-show in-Fig; 2.,but their associatedvrelays such as;rel 25 with armatures such, as armature 3.! are show and it is tobe understooclthat this array of tubes; is associated :withbatteries and relays-as shown; in.:Fig. 1.. In the-telephone. art-thenumbertof leads by..- whichasender, requiresto beconnected to;amarker is knownfor ,each:.-type :of teieph ne sy tem: but may varysomewhat dependent upon typeof-zsystem. This. variance may be ;q considerable. Thegexactnum isgnolip l mary consequence tothisjnvention which isc pable. of associating. a sender with .a .;marlce r any number of conductive leads within reason able limits, for examplegany desired number between land 100. Itwill be seen that such a, system of; conductors designated Csl extends from each sender SI and a similar system C32 exatends froma similarsenderSZ, etc. These con-. ductors all terminate on sets of armatureson th e column of.relay,25... It will be seen thateach. marker has, ex-tendedfltheref rom-a corresponding; set .of conductors and thatwhen any one relay; z5lassociated with any particular marker is. closed, thisv set of conductors is. extended through to the marker; Thus the conductors Cml extend; from the marker-Ml :to: the .-upperrow of front, contacts of relays 25,-.theconductors Cm2jeXe tend to the second row, etc.. It will be seen by extending the array that there may be, any

reasonable number of sendersan-d any reason.-.; ablesnurnber' of markers; Let it now be ,conside' ered that'when anyparticular marker M1,, etc., is idle its associated; relay 2!] isreleased and'i. that'when any particularrsendensi, S2, etc, Ifir quires connection to a marker .its'relay l9 bee; comes energized. It has already been shown by reference to Fig. 1 that only one relay 25 in a column can become energized at the same time and that only one relay, 25 in a row may become energized at the same time. In consequence of this, each sender, when it requires a marker, is connected to one marker and one marker only.

The sender may be connected to the marker for such time and over such leads as is necessary to transfer whatever information is necessary or desirable from the sender to the marker and/or vice versa and to exercise the necessary intercontrol at which time the connection of the sender to the marker is no longer necessary. The marker causes relay 20 to be energized and coincidently causes release of the relay l9 which estabfished the connection to thereby open its contact I if the first column is the one involved. These functions are accomplished by interconnecting relay and circuit means of a nature well understood in the art. The tube T which established this particular connection extinguishes upon the opening of contacts 5 and I3, but it is to be noted that contact 5 remains opened however, by virtue of certain control circuits not shown in the drawings, until after contact I has been opened, to avoid the possibility of the sender causing ionization of another tube. Thereafter, this marker maintains its relay 2!) operated and remains busy until it has performed all its intended functions. Immediately after completion of its functions the marker causes its associated relay 2!! to release. The marker is now again restored to an available condition because contacts 6 and [3 are closed, and all tubes of its row are extinguished.

Consequently, if a sender S1 has been connected with a connector M1 and thereafter requires connection to another marker before marker M1 is idle, sender S1 will become connected with some other marker such as M2 or M3 assuming that some other one is idle. If none is idle the sender will have to wait as will be seen by reference to Fig. 1 because unless and until the pair of circuit establishing elements 8 and. [3 are closed there will be no circuit by which closure of contact I of the first column or the corresponding contacts of other columns can initiate a discharge in any tube of its associated column. It will become apparent that if the markers require more time than the senders to perform their respective functions, it might be necessary to provide a number of markers greater than the number of senders.

In a broad aspect the invention is not limited to interconnection of senders with markers. It

could equally well be employed in analogous manner for the interconnection over a suitable number of conductors from any one of a series of units with any one of a series of other units so that each connection during its existence is unique. The necessity for separate sequencing or allotting circuits or their equivalents are avoided. In other words, the elements of one series such as the senders S1, S2, etc., may close their respective contacts calling for connection with an element of the other series of devices such as the markers M1, M2, etc., in any order and at any time. It is observed that the relays 25 are indicated as multicontact relays. If the number of conductors required to be extended is too great, a plurality of relays 25 may be arranged with their windings in series or multiple to perform the desired function or each relay 25 may control one or more other relays whereby the desired number of conductors may be extended.

In discussing probabilities herein it is to beunderstood that reference is made to exceedingly small probabilities; so small in fact that difiicultyf is encountered in their experimental determination. Although it is difiicult to determine a definite figure for the probability of double connections with a properly designed lock-out circuit of the type of the Bruce application, if We should assume a failure probability of l/n (where n is a large positive integer) the application of the principles of the present invention may further reduce this probability by some factor of the order of 1/10 to 1/10*.

It is to be understood that the above disclosure is exemplary rather than limiting. The scope of the invention is defined by the subjoined claim.

What is claimed is:

An array of tubes coordinately arranged in rows and columns, each tube containing five electrodes, a first group of circuits, one individual to each column, a second group of circuits, one individual to each row, a first impedance common to a first electrode of all tubes in a column, one such impedance for each column, means for initiating a discharge between one of said first electrodes and c fourth electrode, said second impedance limiting said last-mentioned transfer to only one tube in a row, means for transferring said discharge to the space gap between said fourth electrode and a fifth electrode, and means responsive thereto to connect one of said first group' of circuits to one of said second group of circuits.

GEORGE HECHT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,291,036 Hall July 28, 1942 2,291,040 Holden July 28, 1942 2,291,224 Hall July 28, 1942 2,291,752 Parker Aug. 4, 1942 2,326,551 Mohr Aug. 10, 1943 2,348,626 Holden May 9, 1944 2,350,888 Hall June 6, 1944 

